packagej01;

import java.util.Scanner;

public class j05 {

	public static void main(String[] args) {
		 Scanner scanner=new Scanner(System.in);
   	  int a=scanner.nextInt();
   	  if(a/2==0){
   		  System.out.println(a*3);
   	  }else{
   		  System.out.println(a*2);
   		  
   	  }

	}

}
